<%
  update_body_properties = object.settable_properties
  update_body_properties = object.settable_properties.reject(&:input) if object.update_verb == :PATCH
-%>
def updateMask(request, response):
    update_mask = []
<% update_body_properties.each do |v| -%>
    if request.get('<%= v.name -%>') != response.get('<%= v.name -%>'):
        update_mask.append(<%= quote_string(v.name) %>)
<% end -%>
    return ','.join(update_mask)
